Centrifugal bowl



Dec} 19387 G. J. STREZYNSKI I ,1 5

CENTRIFUGAL WL Filed May 18, 193'? 1V C Z\ 7 Eyre 3%; v

Patented Dec. 20, 1938 UNITED STATES PATENT OFFICE CENTRIFUGAL BOWL Application May 18, 1937, Serial No. 143,289

6 Claims.

My invention relates to that type of centrifuges for separating materials of diiferent specific gravities wherein the heavier or heaviest constituent is discharged, either continuously or in- 5 termittently, through ports in the bowl wall.

It is known to provide, in the peripheral wall of the centrifugal bowl, constantly open ports through which the heavier constituent is discharged. To prevent too great a discharge 10 through these ports it is necessary that they be so small that they may be easily clogged by coarse particles,

In a patent granted to me December 3, 1935, No. 2,022,814, I disclose a centrifugal bowl provided with peripheral ports or outlets and a corresponding number of hollow fioatable valve members within the bowl, liquid being controllably admitted to each hollow member to increase its weight and cause it to move outward to close communication between the peripheral part of the bowl and the corresponding outlet, the hollow member having a restricted opening in its outer end adapted to register with said outlet and permit, in its outward position, outflow of liquid from said hollow member through said outlet until the hollow member is sufficiently lightened to cause it to float inward and open communication between the peripheral part of the bowl and embodiment of the invention exhibits certain de- 35 ficiencies which the present invention is adapted to overcome. That specific embodiment comprises valve chambers, open to the interior of the bowl at their radially outermost ends only, each containing a hollow valve having an orifice in its tip and having its radially inward end open for receipt of liquid from its chamber. Such a construction is highly useful and fully operative. However, because these valve bodies must be long enough to reach to approximately the inner wall of liquid in the bowl, they are somewhat diflicult to insert and remove.

When centrifuging some materials as, for instance, secondary sewage sludge,which contains long fibrous material, the ports in the bowl wall sometimes become plugged by such material. If the valves of the above patent open and close frequently they break up this fibrous material at the ports so that it passes through them, but I have found that, in treating this material, these valves have a tendency to eventually become stationary in .a partially open position that continuously throttles the outflow instead of alternately opening wide and closing tight. If this should occur, there would be no hammering or only occasional infrequent hammering, *and the opening might 5 become tightly plugged.

The present invention has for its object to simplify the illustrative embcdimentof the invention disclosed in said patent, secure measurably greater efficiency, and provide a valve which will be more positive and frequent in its hammering action to thereby break up fibrous material. The construction. and mode of operation of the valve member are such that it is practicable to make it so much shorter than the valve member of said patent that it may be easily inserted and removed. In its operation the corresponding outlet port in the peripheral wall of the bowl is closed part of the time and open part of the time, thereby permitting the use of larger ports not so likely to be clogged, and the valve, being in unstable equilibrium, is not likely to assume a stationary throttling position.

In the accompanying drawing, which illustrates a preferred embodiment of the present invention, the figure is a partial vertical section through the bowl.

The bowl shell a and the bowl top b are held together by the usual coupling ring .c. The bowl is supported and driven by a spindle d. A central receiving chamber e has a skirt e spaced from the bowl bottom and having openings 1 through which the entering mixture to be separated flows into the separating chamber of the bowl. A set of conical members g, usually called discs, divides the 'mixture into thin layers while being centrifuged. The outlet for the lightest constituent is at h. The outlet for an intermediate constituent is at i. The heaviest constituent is discharged through outlet ports in the periph- 40 eral wall of the bowl. Only one of these outlet ports is shown. The opening leading to each port 7' is controlled by a valve 7c having a hollow cylindrical body with a conical end having an orifice k at its apex. Each valve 70 is freely movable radially over a block r secured to the bowl shell. A retaining strip s, secured to block 1, limits the inward movement of the valve and has a flange overhanging the rear end of the valve to prevent its tilting from a horizontal position.

Guides, not shown, are provided at the sides of each valve it, to hold it in a radial position.

In operation, the mixture to be separated flows from a feed tube (not shown) into the receiving chamber e and out under its skirt e to and through the holes f. Thence it flows upward and is distributed in the spaces between the discs 9, wherein the constituents are separated. The lightest constituent fiows to the center and thence upward under and inside of a top disc m and escapes at h. The intermediate and heavy constituents fiow to the space around the discs where they separate. The constituent of intermediate weight flows upward between the top disc m and the bowl top I) and escapes at 2 over the inner edge of the control ring it, whence it is discharged through openings 0. When a bowl is to be used for separation of a solid from only a single liquid, as with sewage sludge, the top disc m may be dispensed with and the outlet 1' reduced to the diameter shown for the outlet h.

The heaviest constituent collects within the periphery of the bowl around the valves it. Each valve is, when empty, is so light that it fioats toward the center of the bowl and in that position opens a port :i to allow escape therethrough of heavy separated material. At the same time the port is is opened and liquid flows therethrough into the valve body until the valve and liquid together weigh more than the liquid displaced thereby, whereupon the valve sinks toward the periphery and shuts off communication between the inside of the bowl and the port 9'. The inside of the valve, however, is still in communication with the port 7' and soon discharges until it is so light that it fioats toward the center again and the cycle is repeated. 7

Because the port 7' is closed a considerable portion of the time it may be made much larger than if open all of the time and will therefore be much less liable to be stopped.

Because the valve body is originally filled with air, such air must be compressed to allow inflow of liquid. This resistanceto liquid infiow is not efiective to prevent the admission of a considerable volume or" liquid, since the pressure at its inlet is of the magnitude of several hundred pounds per square inch. Such pressure suifices to compress the air to a small fraction of its original volume and in operation the valve may nearly fill with liquid. This compressed air serves to assist centrifugal force in causing the liquid to fiow out of the valve body while in contact with the seat. With this construction the orifice in the apex of the valve body may be made so large that, under the existing pressures, the valve will alternately fill and empty in such a short time that the movement and the hammering will be very frequent.

While my improved bowl is useful for separating oil, acid sludge and residual acid, for then the lightest and heaviest constituents are liquids and the intermediate constituent is a fiowable sludge, it is adaptable to other uses and it is particularly useful for concentrating the secondary sludge from sewage-disposal plants, which contains large quantities of fibrous, branch-like and hair-like growths.

What I claim and desire to protect by Letters Patent is:

1. The combination with a centrifugal separator bowl having a port through its peripheral wall for the discharge of a heavy constituent, of a hollow valve guidedly movable radially inward and outward and adapted in such movement to alternately open and close communication between the interior of the bowl and the port, said valve having an opening the communication of which with the interior of the bowl is also opened and closed as the valve moves inward and outward but is always in communication with the port, the valve except for said opening being closed, whereby the valve is adapted to be alternately more or less filled and emptied through the same opening, thereby so changing its gross weight that it will alternately sink and fioat in the surrounding liquid.

2. The combination with a centrifugal bowl having a discharge port in its peripheral wall, of a hollow valve having an opening to its interior at only its radially outwardmost portion, said opening being always in communication with said port, said valve adapted to guidedly move radially alternately inward to open communication between the interior of the bowl and both the port and the interior of the valve and outward to close communication between the interior of the bowl and both the port and the interior of the valve, whereby the port is alternately opened and closed and the valve is alternately more or less filled and emptied, causing it to move alternately outward and inward.

3. The combination with a centrifugal bowl having a port through its peripheral wall for the discharge of a heavy constituent, of a hollow valve guidedly movable radially inward and outward to alternately open and close direct communication between the peripheral space of the bowl and said port, said valve being closed except for an opening at its outer end in communication with the peripheral space of the bowl when the valve moves inward to open said port to the peripheral space of the bowl and in such position adapted through said opening to more or less fill with said heavy constituent to thereby so increase its gross weight as to cause it to move outward to close direct communication between the peripheral space of the bowl and said port and in such latter position adapted to more or less empty through said opening and port to thereby so decrease its gross weight as to cause it to again move inward to open direct communication between the peripheral space of the bowl and said port.

4. The combination with a centrifugal bowl having a port through its peripheral wall for the discharge of a heavy constituent, of a hollow valve guidedly movable radially inward and outward to alternately open and close direct communication between the peripheral space of the bowl and said port, said valve having an opening in communication with the peripheral space of the bowl when the valve moves inward to open said port to the peripheral space of the bowl and in such position adapted through said opening to more or less fill with said heavy constituent to thereby so increase its gross weight as to cause it to move outward to close direct communication between the peripheral space of the bowl and said port and in such latter position adapted to more or less. empty through said opening and port to thereby so decrease its gross weight as to cause it to again move inward to open direct communication between the peripheral space of the bowl and said port, said valve, except for said opening, having an imperforate wall.

5. The combination with a "centrifugal separating bowl having a port through its peripheral wall for the discharge of a heavier separated liquid, of a hollow valve guidedly freely movable radially in opposite directions to close and open said port, said valve being closed except for a liquid inflow and outflow orifice in its front end through which said liquid is adapted to enter from the peripheral zone of the bowl when the valve moves inward to open said port and from which such liquid is adapted to discharge through said port when the valve moves outward, whereby the escape of heavier liquid from the peripheral zone of the bowl will be intermittent and whereby said heavier liquid substantially continuously flows through said port either direct from the peripheral zone of the bowl or from the interior of the valve.

6. The combination with a centrifugal separating bowl having a port through its peripheral wall for the discharge of a heavier separated liquid, of a hollow valve guidedly freely movable radially in opposite directions to close and open said port, said valve having a liquid inflow and outflow orifice in its front end through which said liquid is adapted to enter from the peripheral zone of the bowl when the valve moves inward to open said port and from which such liquid is adapted to discharge through said port when the valve moves outward, whereby said heavier liquid substantially continuously flows through said port either direct from the peripheral zone of the bowl or from the interior of the valve, said valve having, except for said front orifice, an imperforate wall,

GEORGE J. STREZYNSKI. 

